Minimally invasive determination of collateral ventilation in lungs

ABSTRACT

Minimally invasive methods, systems and devices are provided for assessing collateral ventilation in the lungs. In particular, collateral ventilation of a target compartment within a lung of a patient is assessed by advancement of a catheter through the tracheobronchial tree to a feeding airway of the target compartment. The feeding airway is occluded by the catheter and the opening and closing of a one-way valve coupled with the catheter is observed. If the valve ceases opening and closing over time, this may indicate that significant collateral ventilation into the target compartment is absent. If the valve continues to open and close over time, significant collateral ventilation into the compartment may be present. Based on the collateral ventilation assessment, a treatment plan may be generated.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/296,951 filed Dec. 7, 2005, the full disclosure of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates generally to respiratory medicine and morespecifically to the field of assessing collateral ventilation pathwaysin the lung and quantitatively determining the resistance of thesecollateral ventilation pathways in the course of diagnosing and treatinglung disease.

Because of recent advances in the treatment of chronic obstructivepulmonary disease (COPD), there has been a heightened interest incollateral ventilation. Various COPD treatments involve the removal oftrapped air to reduce the debilitating hyperinflation caused by thedisease and occlusion of the feeding bronchus to maintain the area at areduced volume. The concept guiding these approaches is that aspirationand/or absorption atelectasis of emphysematous lung regions can reducelung volume without the need to remove tissue. One such type of COPDtreatment, called Endobronchial Volume Reduction (EVR), uses acatheter-based system to reduce lung volume. With the aid of fiberopticvisualization and specialty catheters, a physician can selectivelycollapse a segment or segments of the diseased lung. An occlusal stentis then positioned within the lung segment to prevent the segment fromreinflating.

FIGS. 1A-1C illustrate an example of such an EVR procedure targeting theright upper lobe RUL of the right lung RL of a patient. Here, the rightupper lobe RUL is hyperinflated. A catheter 2 is advanced through thetrachea T into the lung passageways feeding the right upper lobe RUL.The right upper lobe RUL is then reduced in volume, as illustrated inFIG. 1B, and a plug, valve or occlusal stent 4 is placed within the lungpassageway reducing the volume of the right upper lobe RUL. However, asshown in FIG. 1C, collateral channels CH may be present, connecting theright upper lobe RUL with the right middle lobe RML and/or the rightlower lobe RLL. Consequently, the EVR may only be temporarily successfulas the right upper lobe RUL re-expands or re-hyperinflates due to refillthrough the collateral channels CH over time. In some instances,effective EVR may not even be temporarily successful in that appropriatevolume reduction may be impossible due to volume being drawn fromneighboring lobes via the collateral channels CH.

FIGS. 2A-2B schematically illustrate example collateral channels CH inthe right lung RL. FIG. 2A illustrates a variety of inter-lobarcollateral channels CH between the right upper lobe RUL, right middlelobe RML and right lower lobe RLL. FIG. 2B illustrates intra-lobar orinter-segmental collateral channels CH which connect individual lungsegments (e.g. S, S₁, S₂) within the lung lobes. These inter-segmentalcollateral channels allow the periphery of each of the lung compartmentsto communicate with one another and include well-known collateralpathways such as Martin's Channels, pores of Kohn and Lambert's canals.However, in healthy lungs, the main lobes (e.g RUL, RML, RLL) of thelung are typically separated from one another by impermeable fissurescomprised of a double layer of infolded reflections of visceral pleura.Thus, in healthy lungs, collateral channels CH between the lungs areconsidered not present or are minimal. Various anatomic studies haveshown, however, that interlobar fissures frequently do not extendcompletely to the mediastinum or hilum and are, therefore, incomplete.In fact, various studies have described the major fissures to beincomplete in 18% to 73% of cases. As a result, there are varyingdegrees of fusion between lobes, and consequently, these areas ofparenchymal fusion may provide a pathway for the spread of diseasebetween lobes and a pathway for collateral air drift or inter-lobarcollateral ventilation.

Further, a lesser known or rather overlooked fact is that, in thepresence of COPD and emphysema, pathways also develop that traversethrough the fissures thus interconnecting neighboring lung compartments.This has been demonstrated histologically by the use of tantalum gas.Tantalum dust has been shown to accumulate at gaps in the alveolar wallat the lobar junction and to pass through this area in isolated humanlungs, some of which were from emphysema patients. Furthermore, theremay be sufficient collateral air drift across incomplete major fissuresin the dog to prevent atelectasis. Most importantly, the collateralairflow across incomplete major fissures has been measured in normal andemphysematous excised human lungs, and it has been found that inemphysema it is markedly increased. The mechanism that allows for thecreation of these inter-compartment collateral channels has not yet beendocumented in the scientific literature, however, likely contributingfactors are the elastin destruction that occurs in COPD and the tissuestretching that occurs with hyperinflation.

A method of measuring inter-compartment collateral ventilation has beento measure resistance to collateral ventilation (R_(coll)). Assessmentof the relationship between steady-state flow through collateralchannels (Q_(coll)) and the pressure drop across them is a direct wayfor measuring the resistance to collateral ventilation (R_(coll)). Manyinvestigators have attempted to use this approach in the past, but themost simple and versatile way to make this measurement was firstdescribed by Hilpert (Hilpert P., Kollaterale VentilationHabilitationsschirift, aus der Medizinischen. Tubingen, West Germany:Tubingen Universitatsklinik, 1970. Thesis). This method is schematicallyillustrated in FIG. 3A-3C and includes supplying a constant positivepressure of air (P) to a target area or sealed target compartment C_(s).The positive pressure of air is supplied by a positive pressuregenerator 5 through a double-lumen isolation catheter 6 having anisolation cuff 7 which is wedged into a peripheral airway and seals thecompartment C_(s). Therefore, any airflow out of the compartment C_(s)is through collateral channels CH. FIG. 3B illustrates a state of steadypressure P. The method also includes determining the required airflowrate (V_(coll)) to maintain that pressure P. The airflow rate ismeasured by a flowmeter 8 disposed along the isolation catheter 6. Theratio of P over V_(coll) provides a quantitative measure for theresistance to collateral ventilation. It may also be conceived that aconstant airflow (Q_(coll)) may be injected through one lumen of theisolation catheter 6 while air pressure (P_(b)) at the site of bronchialobstruction is measured through the other lumen. Under steady-stateconditions, the ratio between P_(b) and Q_(coll) equals the resistancethrough the collateral system, which includes the resistance in thecollateral channels R_(coll) and the resistance in the small airwaysR_(saw) of the isolated compartment C_(s) between the collateralchannels CH and the distal end of the catheter 6. In either case, thistechnique can be somewhat useful as an experimental tool, however it hassignificant limitations experimentally, and its clinical use poses anadditional risk to the patient. Namely, applying positive pressure orconstant air flow to a diseased area of the lung can be hazardous if notdone correctly. For example in the presence of bullous emphysema, thepressure could enlarge the bullae or create new bulla, or could lead toincreased hyperinflation or pneumothorax.

In another technique, the presence of inter-compartment collateralventilation can be assessed by isolation of the target segment andsubsequent introduction of the subject to breath normally with Heliox(21% O₂/79% He). Detection of tracer gas in the target segment indicatesthe presence of collateral channels communicating that area with therest of the lung.

Experimental attempts to detect the presence of inter-compartmentalcollateral ventilation have also been described recently in exciseddeflated lungs, wherein a lung area is cannulated, sealed andinsufflated with air, while separate neighboring lung areas areconcurrently sealed, and observed to determine whether they inflate.Although this technique can prove very useful in the describedexperimental setting, its clinical practicality is undoubtedly severelylimited for obvious reasons.

Another technique is described in US Patent Application US2003/0228344A1in which a one-way valve is placed in the feeding bronchus of a areatargeted for treatment such that air cannot pass in the inspiratorydirection but can escape in the expiratory direction. The area is thenobserved radiographically to determine if absorption atelectasiseventually occurs; atelectasis would indicate the absence of collateralventilation channels and the lack of atelectasis is alleged to beindicative of the presence of the collateral channels. Unfortunatelythis technique is difficult to practice because the one-way valve maynot generate atelectasis for a variety of reasons such as mucus pluggingof the valve, leakage, improper placement and the lack of a pressuregradient to force trapped air proximally across the valve.

Another method that imposes lesser risk to the patient, relative toHilpert's method, has been described by Woolcock and Macklem (Woolcock,A. J, and P. T. Macklem. Mechanical factors influencing collateralventilation in human, dog, and pig lungs. J. Appl. Physiol. 30:99-115,1971). This method involves the rapid injection of an air bolus beyondthe wedged catheter into the target lung segment, and the rate at whichpressure falls as the obstructed segment empties into the surroundinglung through collateral channels is governed by the time constant forcollateral ventilation τ_(coll) (the time it takes for the pressurechange produced by the air bolus injection to drop to about 37 percentof its initial value). Here R_(coll) is indirectly measured as the ratiobetween τ_(coll) and the compliance of the target segment C_(s).Calculations of R_(coll) via this method, however, are highly dependenton several questionable assumptions, including homogeneity within theobstructed segment and in the surrounding lung. Values for R_(coll)reported in the literature using either Hilpert's method or othermethods range from approximately 10⁻¹ to 10⁺² cmH₂O/(ml/s) for normalhuman lungs and from approximately 10⁻³ to 10⁻¹ cmH₂O/(ml/s) foremphysematous human lungs.

A direct, accurate, simple and minimally invasive method of assessingcollateral flow in lungs that poses minimal risk to the patient isdesired. In addition, methods and devices for quantitatively determiningthe resistance of these collateral ventilation pathways in the course ofdiagnosing and treating lung disease are also desired. At least some ofthese objectives will be met by the present invention.

BRIEF SUMMARY OF THE INVENTION

Minimally invasive methods, systems and devices are provided forqualitatively and quantitatively assessing collateral ventilation in thelungs. In particular, collateral ventilation of a target compartmentwithin a lung of a patient is assessed by advancement of a catheterthrough the tracheobronchial tree to a feeding bronchus of the targetcompartment. The feeding bronchus is occluded by the catheter, and avariety of measurements are taken with the use of the catheter in amanner which is of low risk to the patient. Examples of suchmeasurements include but are not limited to flow rate and pressure.These measurements are used to determine the presence of collateralventilation and to quantify such collateral ventilation. Collateralventilation refers to flow or passage of air from the target lungcompartment into one or more adjacent components through passage(s) inor through the natural barriers which form the components.

Consequently, the lungs of a patient may be analyzed for appropriatenessof various treatment options prior to treatment. For example, levels ofcollateral ventilation may be mapped to various target compartments sothat the practitioner may determine the overall condition of the patientand the most desired course of treatment. If it is desired to performEndobronchial Volume Reduction (EVR) on a lung compartment, the lungcompartment may be analyzed for collateral ventilation prior totreatment to determine the likelihood of success of such treatment.Further, if undesired levels of collateral ventilation are measured, thecollateral ventilation may be reduced to a desired level prior totreatment to ensure success of such treatment. Thus, methods, systemsand devices of the present invention provide advantages overconventional trial-and-error methodologies in which treatment plans aredetermined blindly, without such diagnostic information. This increasesthe likelihood of successful treatment and reduces time, cost andcomplications for the patient.

In a first aspect of the present invention, methods are provided fordiagnosing collateral ventilation between a target lung compartment andadjacent lung compartment(s) in a patient. In some embodiments, themethod comprises isolating a target lung compartment from at least oneadjacent lung compartment (usually all adjacent compartments), allowingthe patient to breathe air free from introduced markers, and detectingair flow or accumulation from the isolated lung compartment over time.Typically, isolating comprises introducing a catheter transtracheally toa main bronchus feeding into the target lung compartment and deployingan occlusion member on the catheter to isolate the target lungcompartment in the main passageway leading into that compartment. Insome instances, detecting may comprise measuring air flow through alumen in the catheter while the patient exhales, wherein said airentered the isolated compartment via collateral passages while thepatient inhaled. In other instances, detecting comprises accumulatingair from the isolated compartment through the catheter over a number ofsuccessive breathing cycles, wherein a continuous increase inaccumulated air volume indicates collateral flow into the isolatedcompartment.

In another aspect of the present invention, methods are provided fordetermining the function or malfunction of an endobronchial prosthesispositioned within a lung passageway of a patient. In some embodiments,the method comprises occluding the lung passageway proximally of theendobronchial prosthesis, allowing the patient to breathe air withoutany markers, and measuring air flow or accumulation from the lungpassageway over time, wherein said measurement is correlative to thefunction or malfunction of the endobronchial prosthesis.

In a further aspect of the present invention, systems are provided fordetecting collateral ventilation into a lung compartment in a patient.In some embodiments, the system comprises a catheter adapted to beintroduced transtracheally to a bronchus leading to a target lungcompartment, an occlusion member on a distal region of the catheter,said occlusion member being adapted to selectively occlude the bronchus,and a flow measurement sensor on the catheter to detect flow of air fromthe isolated compartment as the patient exhales.

In yet another aspect of the present invention, systems are provided fordetecting collateral ventilation into a lung compartment in a patient.In some embodiments, the system comprises a catheter adapted to beintroduced transtracheally to a bronchus leading to a target lungcompartment, an occlusion member or a distal region of the catheter,said occlusion member being adapted to selectively occlude the bronchusand an accumulator connectable to the catheter to accumulate air exhaledfrom the catheter over time. Examples of accumulators include a slackcollection bag which has substantially no resistance to filling withair.

In another aspect of the present invention, methods are provided forevaluating a target lung compartment of a patient. In some embodiments,the method comprises positioning an instrument within a lung passagewayleading to the target lung compartment so that the target lungcompartment is isolated, injecting an inert gas into the isolated targetlung compartment, generating at least one measurement of pressure withinthe target lung segment, generating at least one measurement ofconcentration of inert gas within the target lung segment, and analyzingthe at least one target lung compartment with the use of the at leastone measurement of pressure and the at least one measurement ofconcentration of inert gas. Analyzing may comprise determining a degreeof hyperinflation. In such instances, the method may further comprisedetermining a treatment plan at least partially based on the determineddegree of hyperinflation. Alternatively or in addition, analyzing maycomprise determining a state of compliance. In such instances, themethod may further comprise determining a treatment plan at leastpartially based on the determined state of compliance. Likewise,analyzing may comprise determining a collateral resistance. In suchinstances, the method may further comprise determining a treatment planbased on the determined collateral resistance.

In some embodiments, generating the at least one measurement of pressurecomprises generating a plurality of measurements of pressure over apredetermined time period. The predetermined time period may comprise,for example, approximately one minute. In some embodiments, generatingthe at least one measurement of concentration of inert gas comprisesgenerating a plurality of measurements of concentration of inert gasover a predetermined time period. In some embodiments, the inert gas maycomprise helium.

In another aspect of the present invention, systems are provided forevaluating a target lung compartment comprising an instrumentpositionable within a lung passageway leading to the target lungcompartment so that the target lung compartment is isolated, wherein theinstrument includes a mechanism for injecting an inert gas to the targetlung segment, at least one sensor which generates measurement datareflecting pressure within the target lung segment, and at least onesensor which generates measurement data reflecting concentration of aninert gas within the target lung segment. In some embodiments, thesystem further comprises a processor which performs computations withthe use of the measurement data reflecting pressure and the measurementdata reflecting concentration of inert gas. In these embodiments, thecomputations may include calculating a degree of hyperinflation of thetarget lung compartment, calculating a state of compliance of the targetlung compartment, and/or calculating collateral resistance of the targetlung compartment. The measurement data reflecting pressure may comprisegenerating a plurality of measurements of pressure over a predeterminedtime period. In some instances, the predetermined time period comprisesapproximately one minute. The measurement data reflecting concentrationof inert gas may comprise generating a plurality of measurements ofconcentration of inert gas over a predetermined time period. In someembodiments, the inert gas may comprise helium.

In another aspect of the present invention, treatment guides areprovided to determine a course of treatment for a lung compartment of apatient. In some embodiments, the guide comprises a plurality ofhyperinflation values, each hyperinflation value representing a degreeof hyperinflation of the lung compartment, and/or a plurality ofcompliance values, each compliance value representing a degree ofcompliance of the lung compartment, and a plurality of treatmentoptions, wherein each treatment option is correlated to a hyperinflationvalue and/or a compliance value. Typically, the guide comprises acomputer program. In such instances, the computer program includes atleast one mathematical computation to generate the plurality ofhyperinflation values and/or the plurality of compliance values. Themathematical computation may utilize, for example, pressure andconcentration of inert gas values.

In still another aspect of the present invention, methods of evaluatingcollateral ventilation of a target lung compartment of a patient areprovided. In some embodiments, the method includes positioning aninstrument within a lung passageway leading to the target lungcompartment so that the target lung compartment is isolated, allowingthe patient to inhale air, generating at least one measurement of atleast one characteristic of the inhaled air within or exiting the targetlung compartment with the use of the instrument, and determining a levelof collateral ventilation into the target lung compartment based on theat least one measurement. Typically, the at least one characteristicincludes volumetric flow rate and pressure. Determining a level ofcollateral ventilation may include calculating a value of collateralresistance. The method may further comprise determining a treatment planbased on the level of collateral ventilation.

In yet another aspect of the present invention, a method is provided forevaluating a patient for treatment of a target lung compartment, themethod comprising generating at least one measurement associated withthe target lung compartment while the patient is breathing air,calculating a level of collateral ventilation into the target lungcompartment based on the at least one measurement, and treating thepatient based on the calculated level of collateral ventilation.Treating the patient may comprise aspirating the target lungcompartment. Alternatively or in addition, treating the patient maycomprise occluding a lung passageway feeding the target lungcompartment. Typically, occluding comprises positioning an occlusalstent within the lung passageway. Calculating may comprise calculating avalue of collateral resistance based on the at least one measurement.

In a further aspect of the present invention, additional treatmentguides are provided to determine a course of treatment for a lungcompartment of a patient. In some embodiments, the guide comprises aplurality of collateral resistance values, each value representingdegree of collateral ventilation of the lung compartment, and aplurality of treatment options, wherein each treatment option iscorrelated to a collateral resistance value. Typically, the guidecomprises a computer program. In such instances, the computer programmay include at least one mathematical computation to generate theplurality of collateral resistance values. The mathematical computationmay utilize pressure and volumetric flow rate values. In someembodiments, the guide also includes a visual display showing a curverepresenting a relationship between the collateral resistance values anda combination of the pressure and volumetric flow rates.

In another aspect of the present invention, a method is provided fordetermining presence or absence of collateral ventilation between lungcompartments in a patient. The method generally involves: introducing acatheter transtracheally to a airway feeding into a target lungcompartment; deploying an occlusion member on the catheter in the airwayto prevent inhaled air from traveling into the target lung compartmentthrough the airway while allowing exhaled air to leave the target lungcompartment through a lumen of the catheter; allowing the patient tobreathe; observing opening and closing of a one-way valve coupled with aproximal portion of the catheter and in fluid communication with thecatheter lumen, wherein the one-way valve is located outside thepatient; and determining the presence or absence of collateralventilation into the target lung compartment from one or more adjacentlung compartments, based on the observed opening and closing of theone-way valve over time.

Generally, the opening and closing of the one-way valve may be observedover a period of time sufficient to allow breathing by the patient toeither significantly empty the target lung compartment of air if thereis no significant collateral ventilation into the target lungcompartment or to fail to empty the target lung compartment if there issignificant collateral ventilation. Thus, in some cases it may bedecided that significant collateral ventilation into the target lungcompartment is absent if the one-way valve stops opening and closingduring the period of time. Conversely, in other cases it may be decidedthat significant collateral ventilation into the target lung compartmentis present if the one-way valve continues opening and closing throughoutthe period of time.

In some embodiments, the opening and closing of the one-way valve may beobserved via the naked eye. Alternatively, in other embodiments, theopening and closing of the valve may be observed using one or morevisualization devices, such as a video camera aimed at the valve. Insome embodiments, the visualization devices may include a video monitorfor displaying the video image captured by the camera.

In addition to observing the opening and closing of the one-way valve,in some embodiments the method may further involve measuring at leastone parameter via the catheter. For example, in some embodimentscollateral resistance may be measured.

In another aspect of the present invention, a system for detectingcollateral ventilation into a lung compartment in a patient may include:a catheter having a lumen and adapted to be introduced transtracheallyto a bronchus leading to a target lung compartment; an occlusion memberon a distal region of the catheter, said occlusion member being adaptedto selectively occlude the bronchus; and a one-way valve coupled with aproximal region of the catheter and in fluid communication with thelumen. In this system, the occlusion member, when deployed in thebronchus, prevents air from being inhaled into the target lungcompartment through the bronchus, while the catheter allows air exhaledfrom the target lung compartment to pass through the lumen and theone-way valve. The catheter also has sufficient overall length so thatthe one-way valve is located outside the patient during use.

In some embodiments, the system may also include a video camera adaptedto capture video images of the one-way valve. In one embodiment, forexample, the video camera may be a USB camera. Also in some embodimentsthe video camera may be coupled with the proximal region of thecatheter. In some embodiments, the video camera may be coupled with ahousing member, with the one-way valve and proximal region of thecatheter also being coupled with the housing member. Some embodiments ofthe system may also include a video monitor for displaying the videoimages captured by the video camera.

In one embodiment, the one-way valve may be removably coupled with thecatheter. For example, in one embodiment the one-way valve may be anendobronchial valve device. In some embodiments, the one-way valve maybe housed inside a housing member that is removably coupled with theproximal region of the catheter. In some embodiments, the system mayfurther include a filter coupled with the catheter to filter exhaled airtraveling through the catheter to the valve. In such embodiments, atleast a portion of the catheter distal to the filter may be removablefrom the system, so that the valve may be used in multiple patientswithout fear of contamination.

Other objects and advantages of the present invention will becomeapparent from the detailed description to follow, together with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C illustrate an example of an EVR procedure targeting theright upper lobe of the right lung of a patient.

FIGS. 2A-2B schematically illustrate example collateral channels in theright lung.

FIGS. 3A-3C schematically illustrates a method of supplying constantpositive pressure of air to a target compartment.

FIGS. 4A-4D illustrate an embodiment of a minimally invasive method inwhich a catheter is advanced to the feeding bronchus of a targetcompartment.

FIGS. 5A-5D, 6 illustrate embodiments of a catheter connected with anaccumulator.

FIGS. 7A-7B depict a graphical representation of a simplified collateralsystem of a target lung compartment.

FIGS. 8A-8C illustrate measurements taken from the system of FIGS.7A-7B.

FIGS. 9A-9C illustrate a circuit model representing the system of FIGS.7A-7B.

FIGS. 10A-10B illustrate measurements taken from the system of FIGS.7A-7B.

FIGS. 11A-11D illustrate graphical comparisons yielded from thecomputational model of the collateral system illustrated in FIGS. 7A-7Band FIGS. 9A-9B.

FIG. 12A illustrates a two-compartment model which is used to generate amethod quantifying the degree of collateral ventilation.

FIG. 12B illustrates an electrical circuit analog model.

FIGS. 12C-12E illustrate the resulting time changes in volumes,pressures and gas concentrations in the target compartment and the restof the lobe.

FIGS. 13A-13C illustrate changes in measured variables based on degreeof effort.

FIGS. 14A-14B illustrate changes in measured variables based onfrequency of effort.

FIGS. 15, 16A-16B illustrate the use of continuous positive airwaypressure to assist in the detection of collateral ventilation.

FIG. 17 illustrates a single breath technique.

FIGS. 18A-18C illustrate example flow, volume and pressure measurementcurves respectively.

FIG. 19 illustrates flow measured via a catheter wherein differences inthe waveform characteristic of inspiration versus exhalation facilitatedetermining whether collateral ventilation exists.

FIGS. 20A-20B illustrate an embodiment of an isolation catheterincluding a bronchoscope.

FIGS. 21A-21C illustrate the performance of a collateral ventilationtest through an occlusal stent.

FIGS. 22A-22C illustrate the use of carbon dioxide to indicatecollateral flow.

FIGS. 23A-23C illustrate the use of tracer gas to indicate collateralflow.

FIGS. 24A-24C illustrate the use of oxygen to indicate collateral flow.

FIGS. 25A-25C illustrate methods and devices for seal testing of anisolation catheter.

FIG. 26 illustrates an embodiment of a system of the present inventionfor measuring collateral ventilation in one or more lung passageways.

FIG. 27 illustrates an embodiment of a screen indicating collateralventilation measurements and mapping.

FIG. 28 illustrates an embodiment of a method of treating a patient.

FIG. 29 illustrates an example iterative process of reducing collateralventilation prior to EVR.

FIGS. 30A-30D illustrate various views of a system for determining thepresence or absence of collateral ventilation into a target portion of alung according to one embodiment.

DETAILED DESCRIPTION OF THE INVENTION

Minimally invasive methods, systems and devices are provided forqualitatively and quantitatively assessing collateral ventilation in thelungs. FIGS. 4A-4D illustrate an embodiment of a minimally invasivemethod in which a catheter 10 is advanced through a tracheobronchialtree to the feeding bronchus B of the target area C_(s), the compartmenttargeted for treatment or isolation. The catheter 10 comprises a shaft12 having at least one lumen therethrough and an occlusion member 14mounted near its distal end. The catheter 10 is equipped to seal thearea between the catheter shaft 12 and the bronchial wall such that onlya lumen inside the catheter which extends the entire length of thecatheter is communicating with the airways distal to the seal. The seal,or isolation, is accomplished by the use of the occlusion member 14,such as an inflatable member, attached to the distal tip of the catheter10.

On the opposite end of the catheter 10, external to the body of thepatient, a one-way valve 16, a flow-measuring device 18 or/and apressure sensor 20 are placed in series so as to communicate with thecatheter's inside lumen. The one-way valve 16 prevents air from enteringthe target compartment C_(s) from atmosphere but allows free airmovement from the target compartment C_(s) to atmosphere. When there isan absence of collateral channels connecting the targeted isolatedcompartment C_(s) to the rest of the lung, as illustrated in FIGS.4A-4B, the isolated compartment C_(s) will unsuccessfully attempt todraw air from the catheter lumen during inspiration of normalrespiration of the patient. Hence, during exhalation no air is returnedto the catheter lumen. In the presence of collateral channels, asillustrated in FIGS. 4C-4D, an additional amount of air is available tothe isolated compartment C_(s) during the inspiratory phase of eachbreath, namely the air traveling from the neighboring compartment(s) Cthrough the collateral channels CH, which enables volumetric expansionof the isolated compartment C_(s) during inspiration, resulting duringexpiration in air movement away from the isolated compartment C_(s) toatmosphere through the catheter lumen and the collateral channels CH.Thus, air is expelled through the catheter lumen during each exhalationand will register as positive airflow on the flow-measuring device 18.This positive airflow through the catheter lumen provides an indicationof whether or not there is collateral ventilation occurring in thetargeted compartment C_(s).

This technique of measuring collateral flow in a lung compartment isanalogous to adding another lung compartment, or lobe with infinitelylarge compliance, to the person's lungs, the added compartment beingadded externally. Depending on the system dynamics, some air may beexpelled through the catheter lumen during exhalation in the absence ofcollateral channels, however at a different rate, volume and trend thanthat in the presence of collateral channels.

In other embodiments, the catheter 10 is connected with an accumulatoror special container 22 as illustrated in FIGS. 5A-5D, 6. The container22 has a very low resistance to airflow, such as but not limited to e.g.a very compliant bag or slack collection bag. The container 22 isconnected to the external end or distal end 24 of the catheter 10 andits internal lumen extending therethrough in a manner in which theinside of the special container 22 is communicating only with theinternal lumen. During respiration, when collateral channels are notpresent as illustrated in FIGS. 5A-5B, the special container 22 does notexpand. The target compartment Cs is sealed by the isolation balloon 14so that air enters and exits the non-target compartment C. Duringrespiration, in the presence of collateral channels as illustrated inFIGS. 5C-5D, the special container 22 will initially increase in volumebecause during the first exhalation some portion of the airflow receivedby the sealed compartment C_(s) via the collateral channels CH will beexhaled through the catheter lumen into the external special container22. The properties of the special container 22 are selected in order forthe special container 22 to minimally influence the dynamics of thecollateral channels CH, in particular a highly inelastic specialcontainer 22 so that it does not resist inflation. Under the assumptionthat the resistance to collateral ventilation is smaller duringinspiration than during expiration, the volume in the special container22 will continue to increase during each subsequent respiratory cyclebecause the volume of air traveling via collateral channels CH to thesealed compartment C_(s) will be greater during inspiration than duringexpiration, resulting in an additional volume of air being forcedthrough the catheter lumen into the special container 22 duringexhalation.

Optionally, a flow-measuring device 18 or/and a pressure sensor 20 maybe included, as illustrated in FIG. 6. The flow-measuring device 18and/or the pressure sensor 20 may be disposed at any location along thecatheter shaft 12 (as indicated by arrows) so as to communicate with thecatheter's internal lumen. When used together, the flow-measuring device18 and the pressure sensor 20 may be placed in series. A one-way valve16 may also be placed in series with the flow-measuring device 18 or/andpressure sensor 20. It may be appreciated that the flow-measuring device18 can be placed instead of the special container 22 or between thespecial container 22 and the isolated lung compartment, typically at butnot limited to the catheter-special container junction, to measure theair flow rate in and out of the special container and hence byintegration of the flow rate provide a measure of the volume of airflowing through the catheter lumen from/to the sealed compartment C_(s).

It can be appreciated that measuring flow can take a variety of forms,such as but not limited to measuring flow directly with theflow-measuring device 18, and/or indirectly by measuring pressure withthe pressure sensor 20, and can be measured anywhere along the cathetershaft 12 with or without a one-way valve 16 in conjunction with the flowsensor 18 and with or without an external special container 22.

Furthermore, a constant bias flow rate can be introduced into the sealedcompartment C_(s) with amplitude significantly lower than the flow rateexpected to be measured due to collateral flow via the separate lumen inthe catheter 10. For example, if collateral flow measured at the flowmeter 18 is expected to be in the range of 1 ml/min, the bias flow ratecan be, but not limited to one tenth (0.1) or one one-hundredth (0.01)of that amount of equal or opposite amplitude. The purpose of the biasflow is to continuously detect for interruptions in the detectioncircuit (i.e., the working channel of the bronchoscope and any othertubing between the flow meter and catheter) such as kinks or clogs, andalso to increase response time in the circuit (due to e.g. inertia).Still, a quick flush of gas at a high flow rate (which is distinguishedfrom the collateral ventilation measurement flow rate) can periodicallybe introduced to assure an unclogged line.

In addition to determining the presence of collateral ventilation of atarget lung compartment, the degree of collateral ventilation may bequantified by methods of the present invention. In one embodiment, thedegree of collateral ventilation is quantified based on the resistancethrough the collateral system R_(coll). R_(coll) can be determined basedon the following equation:

$\begin{matrix}{{\frac{\overset{\_}{P_{b}}}{\overset{\_}{Q_{fm}}}} = {R_{coll} + R_{saw}}} & (1)\end{matrix}$where R_(coll) constitutes the resistance of the collateral channels,R_(saw) characterizes the resistance of the small airways, and P_(b) andQ_(fm) represent the mean pressure and the mean flow measured by acatheter isolating a target lung compartment in a manner similar to thedepictions of FIGS. 4A-4D.

For the sake of simplicity, and as a means to carry out a proof ofprinciple, FIGS. 7A-7B depict a graphical representation of a simplifiedcollateral system of a target lung compartment C_(s). A single elasticcompartment 30 represents the target lung compartment C_(s) and issecurely positioned inside a chamber 32 to prevent any passage of airbetween the compartment 30 and the chamber 32. The chamber 32 can bepressurized to a varying negative pressure relative to atmosphere,representing the intrathoracic pressure P_(pl). The elastic compartment30, which represents the target compartment in the lung C_(s),communicates with the atmospheric environment through passageway 40. Inaddition, the elastic compartment 30 also communicates with theatmospheric environment through collateral pathway 41, representingcollateral channels CH of the target compartment of the lung C_(s).

A catheter 34 is advanceable through the passageway 40, as illustratedin FIGS. 7A-7B. The catheter 34 comprises a shaft 36, an inner lumen 37therethrough and an occlusion member 38 mounted near it's distal end.The catheter 34 is specially equipped to seal the area between thecatheter shaft 36 and the passageway 40 such that only the lumen 37inside the catheter 34, which extends the length of the catheter 34,allows for direct communication between the compartment 30 andatmosphere. On the opposite end of the catheter 34, a flow-measuringdevice 42 and a pressure sensor 44 are placed in series to detectpressure and flow in the catheter's inside lumen 37. A one-way valve 48positioned next to the flow measuring device 42 allows for the passageof air in only one direction, namely from the compartment 30 toatmosphere. The flow measuring device 42, the pressure sensor device 44and the one-way valve 48 can be placed anywhere along the length of thecatheter lumen, typically at but not limited to the proximal end of thecatheter shaft 36. It should be appreciated that measuring pressureinside the compartment 30 can be accomplished in a variety of forms,such as but not limited to connecting the pressure sensor 44 to thecatheter's inside lumen 37. For instance, it can also be accomplished byconnecting the pressure sensor 44 to a separate lumen inside thecatheter 34, which extends the entire length of the catheter 34communication with the airways distal to the seal.

At any given time, the compartment 30 may only communicate to atmosphereeither via the catheter's inside lumen 37 representing R_(saw) and/orthe collateral pathway 41 representing R_(coll). Accordingly, duringinspiration, as illustrated in FIG. 7A, P_(pl) becomes increasinglynegative and air must enter the compartment 30 solely via collateralchannels 41. Whereas during expiration, illustrated in FIG. 7B, air mayleave via collateral channels 41 and via the catheter's inside lumen 37.

FIGS. 8A-8C illustrate measurements taken from the system of FIGS. 7A-7Bduring inspiration and expiration phases. FIG. 8A illustrates acollateral flow curve 50 reflecting the flow Q_(coll) through thecollateral pathway 41. FIG. 8B illustrates a catheter flow curve 52reflecting the flow Q_(fm) through the flow-measuring device 42. Duringinspiration, air flows through the collateral pathway 41 only; no airflows through the flow-measuring device 42 since the one-way valve 48prevents such flow. Thus, FIG. 8A illustrates a negative collateral flowcurve 50 and FIG. 8B illustrates a flat, zero-valued catheter flow curve52. During expiration, a smaller amount of air, as compared to theamount of air entering the target compartment Cs during inspiration,flows back to atmosphere through the collateral pathway 41, asillustrated by the positive collateral flow curve 50 of FIG. 8A, whilethe remaining amount of air flows through the catheter lumen 37 back toatmosphere, as illustrated by the positive catheter flow curve 52 ofFIG. 8B.

The volume of air flowing during inspiration and expiration can bequantified by the areas under the flow curves 50, 52. The total volumeof air V₀ entering the target compartment 30 via collateral channels 41during inspiration can be represented by the colored area under thecollateral flow curve 50 of FIG. 8A. The total volume of air V₀ may bedenoted as V₀=V₁+V₂, whereby V₁ is equal to the volume of air expelledvia the collateral channels 41 during expiration (indicated by thegrey-colored area under the collateral flow curve 50 labeled V₃), and V₂is equal to the volume of air expelled via the catheter's inside lumen37 during expiration (indicated by the colored area under the catheterflow curve 52 of FIG. 8B labeled V₄).

The following rigorous mathematical derivation demonstrates the validityof theses statements and the relation stated in Eq. 1:

Conservation of mass states that in the short-term steady state, thevolume of air entering the target compartment 30 during inspiration mustequal the volume of air leaving the same target compartment 30 duringexpiration, henceV ₀=−(V ₃ +V ₄)  (2)Furthermore, the mean rate of air entering and leaving the targetcompartment solely via collateral channels during a complete respiratorycycle (T_(resp)) can be determined as

$\begin{matrix}{\overset{\_}{Q_{coll}} = {\frac{V_{0} + V_{3}}{T_{resp}} = \frac{V_{2}}{T_{resp}}}} & (3)\end{matrix}$where V₂ over T_(resp) represents the net flow rate of air entering thetarget compartment 30 via the collateral channels 41 and returning toatmosphere through a different pathway during T_(resp). Accordingly, V₂accounts for a fraction of V₀, the total volume of air entering thetarget compartment 30 via collateral channels 41 during T_(resp), henceV₀ can be equally defined in terms of V₁ and V₂ asV ₀ =V ₁ +V ₂  (4)where V₁ represents the amount of air entering the target compartment 30via the collateral channels 41 and returning to atmosphere through thesame pathway. Consequently, substitution of V₀ from Eq. 4 into Eq. 3yieldsV ₁ =−V ₃  (5)and substitution of V₀ from Eq. 2 into the left side of Eq. 4 followingsubstitution of V₁ from Eq. 5 into the right side of Eq. 4 results in−V ₄ =V ₂  (6)Furthermore, the mean flow rate of air measured at the flowmeter 42during T_(resp) can be represented as

$\begin{matrix}{\overset{\_}{Q_{fm}} = \frac{V_{4}}{T_{resp}}} & (7)\end{matrix}$where substitution of V₄ from Eq. 6 into Eq. 7 yields

$\begin{matrix}{\overset{\_}{Q_{fm}} = {{- \frac{V_{2}}{T_{resp}}} = {- \overset{\_}{Q_{coll}}}}} & (8)\end{matrix}$

Ohms's law states that in the steady stateP _(s) = Q _(coll) ·R _(coll)  (9)where P_(s) represents the mean inflation pressure in the targetcompartment required to sustain the continuous passage of Q_(coll)through the resistive collateral channels represented by R_(coll).Visual inspection of the flow and pressure signals (FIG. 8C) within asingle T_(resp) shows that during the inspiratory time, P_(b)corresponds to P_(s) since no air can enter or leave the isolatedcompartment 30 via the catheter's inside lumen 37 during the inspiratoryphase. During expiration, however, P_(b)=0 since it is measured at thevalve opening where pressure is atmospheric, while P_(s) must stillovercome the resistive pressure losses produced by the passage of Q_(fm)through the long catheter's inside lumen 37 represented by R_(saw)during the expiratory phase effectively making P_(s) less negative thanP_(b) by Q_(fm) ·R_(saw). AccordinglyP _(s) = P _(b) + Q _(fm) ·R _(saw)  (10)and substitution of P_(s) from Eq. 9 into Eq. 10 results inP _(b) = Q _(coll) ·R _(coll)− Q _(fm) ·R _(saw)  (11)after subsequently solving for P_(b) . Furthermore, substitution ofQ_(coll) from Eq. 8 into Eq. 11 yieldsP _(b) =− Q _(fm) ·(R _(coll) +R _(saw))  (12)and division of Eq. 12 by Q_(fm) finally results in

$\begin{matrix}{\frac{\overset{\_}{P_{b}}}{\overset{\_}{Q_{fm}}} = {- \left( {R_{coll} + R_{saw}} \right)}} & (13)\end{matrix}$where the absolute value of Eq. 13 leads back to the aforementionedrelation originally stated in Eq. 1.

The system illustrated in FIGS. 7A-7B can be represented by a simplecircuit model as illustrated in FIGS. 9A-9C. The air storage capacity ofthe alveoli confined to the isolated compartment 30 representing C_(s)is designated as a capacitance element 60. The pressure gradient(P_(s)−P_(b)) from the alveoli to atmosphere via the catheter's insidelumen 37 is caused by the small airways resistance, R_(saw), and isrepresented by resistor 64. The pressure gradient from the alveoli toatmosphere through the collateral channels is generated by theresistance to collateral flow, R_(coll), and is represented by resistor62.

Accordingly, the elasticity of the isolated compartment 30 isresponsible for the volume of air obtainable solely across R_(coll)during the inspiratory effort and subsequently delivered back toatmosphere through R_(saw) and R_(coll) during expiration. Pressurechanges during respiration are induced by the variable pressure source,P_(pl) representing the varying negative pleural pressure within thethoracic cavity during the respiratory cycle. An ideal diode 66represents the one-way valve 48, which closes during inspiration andopens during expiration. Consequently, as shown in FIGS. 10A-10B, theflow measured by the flow meter (Q_(fm)) is positive during expirationand zero during inspiration, whereas the pressure recorded on thepressure sensor (P_(b)) is negative during inspiration and zero duringexpiration.

Evaluation of Eqs. 1 & 8 by implementation of a computational model ofthe collateral system illustrated in FIGS. 7A-7B and FIGS. 9A-9C yieldsthe graphical comparisons presented in FIGS. 11A-11D. FIG. 11A displaysthe absolute values of mean Q_(fm) (| Q_(fm) |) and mean Q_(coll) (|Q_(coll) |) while the FIG. 11B shows the model parametersR_(coll)+R_(saw) plotted together with | P_(b) / Q_(coll) | as afunction of R_(coll). The values denote independent realizations ofcomputer-generated data produced with different values of R_(coll) whileR_(saw) is kept constant at 1 cmH₂O/(ml/s). FIG. 11A displays theabsolute values of | Q_(fm) | and | Q_(coll) | while FIG. 11C shows themodel parameters R_(coll)+R_(saw) plotted together with | P_(b) /Q_(coll) | as a function of R_(saw). The values denote independentrealizations of computer-generated data produced with different valuesof R_(saw) while R_(coll) is kept constant at 1 cmH₂O/(ml/s). It becomesquite apparent from FIGS. 11A-11B that the flow is maximal whenR_(coll)≈R_(saw) and diminishes to zero as R_(coll) approaches thelimits of either “overt collaterals” or “no collaterals”. Accordingly,small measured flow Q_(fm) can mean both, very small and very largecollateral channels and hence no clear-cut decision can be maderegarding the existence of collateral ventilation unlessR_(coll)+R_(saw) is determined as | P_(b) / Q_(fm) |. The reason forthis is that when R_(coll) is very small compared to R_(saw), all gasvolume entering the target compartment via the collateral channelsleaves via the same pathway and very little gas volume is left to travelto atmosphere via the small airways as the isolated compartment empties.The measured pressure P_(b), however, changes accordingly andeffectively normalizes the flow measurement resulting in an accuraterepresentation of R_(coll)+R_(saw), which is uniquely associated withthe size of the collateral channels and the correct degree of collateralventilation.

Similarly, FIGS. 11C-11D supplement FIGS. 11A-11B as it shows how themeasured flow Q_(fm) continuously diminishes to zero as R_(saw) becomesincreasingly greater than R_(coll) and furthermore increases to amaximum, as R_(saw) turns negligible when compared to R_(coll). WhenR_(saw) is very small compared to R_(coll), practically all gas volumeentering the target compartment via the collateral channels travels backto atmosphere through the small airways and very little gas volume isleft to return to atmosphere via the collateral channels as the isolatedcompartment empties. Thus, determination of | P_(b) / Q_(fm) | resultsin an accurate representation of R_(coll)+R_(saw) regardless of theunderlying relation amongst R_(coll) and R_(saw). In a healthy human,resistance through collateral communications, hence R_(coll), supplyinga sublobar portion of the lung is many times (10-100 times) as great asthe resistance through the airways supplying that portion, R_(saw)(Inners 1979, Smith 1979, Hantos 1997, Suki 2000). Thus in the normalindividual, R_(coll) far exceeds R_(saw) and little tendency forcollateral flow is expected. In disease, however, this may not be thecase (Hogg 1969, Terry 1978). In emphysema, R_(saw) could exceedR_(coll) causing air to flow preferentially through collateral pathways.

Therefore, the above described models and mathematical relationships canbe used to provide a method which indicates the degree of collateralventilation of the target lung compartment of a patient, such asgenerating an assessment of low, medium or high degree of collateralventilation or a determination of collateral ventilation above or belowa clinical threshold. In some embodiments, the method also quantifiesthe degree of collateral ventilation, such generating a value whichrepresents R_(coll). Such a resistance value indicates the geometricsize of the collateral channels in total for the lung compartment. Basedon Poiseuille's Law with the assumption of laminar flow,R∝(η×L)/r ⁴  (14)wherein η represents the viscosity of air, L represents the length ofthe collateral channels and r represents the radius of the collateralchannels. The fourth power dependence upon radius allows an indicationof the geometric space subject to collateral ventilation regardless ofthe length of the collateral channels.

FIG. 12A illustrates a two-compartment model which is used to generate amethod quantifying the degree of collateral ventilation, including a)determining the resistance to segmental collateral flow R_(coll), b)determining the state of segmental compliance C_(s), and c) determiningthe degree of segmental hyperinflation q_(s). Again, C_(s) characterizesthe compliance of the target compartment or segment. C_(L) representsthe compliance of the rest of the lobe. R_(coll) describes theresistance to the collateral airflow. FIG. 12B provides an electricalcircuit analog model. In this example, at time t=t₁, approximately 5-10ml of 100% inert gas such as He (q_(he)) is infused. After a period oftime, such as one minute, the pressure (P_(S)) & the fraction of He(F_(he) _(s) ) are measured.

The dynamic behavior of the system depicted in FIGS. 12A-12B can bedescribed by the time constant τ_(coll)

$\begin{matrix}{\tau_{coll} = {R_{coll} \cdot \frac{C_{S}C_{L}}{\underset{C_{s}}{\underset{︸}{C_{S} + C_{L}}}}}} & (15)\end{matrix}$

At time t₁=30 s, a known fixed amount of inert gas (q_(he): 5-10 ml of100% He) is rapidly injected into the target compartment C_(s), whilethe rest of the lobe remains occluded, and the pressure (P_(S)) and thefraction of He (F_(he) _(S) ) are measured in the target segment forapproximately one minute (T=60 s). FIGS. 12C-12E illustrate theresulting time changes in volumes, pressures and gas concentrations inthe target compartment C_(s) and the rest of the lobe C_(L). Eqs. 16-21state the mathematical representation of the lung volumes, pressures andgas concentrations at two discrete points in time, t₁ and t₂.

$\begin{matrix}{{q_{s}\left( t_{1} \right)} = {{q_{s}(0)} + q_{he}}} & (16) \\{{{q_{s}\left( t_{2} \right)} + {q_{L}\left( t_{2} \right)}} = {{q_{s}(0)} + {q_{L}(0)} + q_{he}}} & (17) \\{{P_{s}\left( t_{1} \right)} = \frac{q_{he}}{C_{s}}} & (18) \\{{P_{s}\left( t_{2} \right)} = \frac{q_{he}}{\left( {C_{s} + C_{L}} \right)}} & (19) \\{{F_{{he}_{s}}\left( t_{1} \right)} = \frac{q_{he}}{q_{s}\left( t_{1} \right)}} & (20) \\{{F_{{he}_{s}}\left( t_{2} \right)} = \frac{q_{he}}{{q_{s}\left( t_{1} \right)} + {q_{L}\left( t_{2} \right)}}} & (21)\end{matrix}$

As a result, the following methods may be performed for each compartmentor segment independently: 1) Assess the degree of segmentalhyperinflation, 2) Determine the state of segmental compliance, 3)Evaluate the extent of segmental collateral communications.

Segmental Hyperinflation.

The degree of hyperinflation in the target segment, q_(S)(0), can bedetermined by solving Eq. 16 for q_(S)(0) and subsequently substitutingq_(S)(t₁) from Eq. 20 into Eq. 16 after appropriate solution of Eq. 20for q_(S)(t₁) as

$\begin{matrix}{{q_{S}(0)} = {q_{he} \cdot \left( \frac{1 - {F_{{he}_{s}}\left( t_{1} \right)}}{F_{{he}_{s}}\left( t_{1} \right)} \right)}} & (22)\end{matrix}$

Segmental Compliance.

The state of compliance in the target segment, C_(S), can be determinedsimply by solving Eq. 18 for C_(S) as

$\begin{matrix}{C_{S} = \frac{q_{he}}{P_{S}\left( t_{1} \right)}} & (23)\end{matrix}$

Segmental Collateral Resistance.

A direct method for the quantitative determination of collateral systemresistance in lungs, has been described above. Whereas, the calculationbelow offers an indirect way of determining segmental collateralresistance.

The compliance of the rest of the lobe, C_(L), can be determined bysolving Eq. 19 for C_(L) and subsequently substituting C_(S) with Eq.23. Accordingly

$\begin{matrix}{C_{L} = {q_{he} \cdot \frac{{P_{S}\left( t_{1} \right)} - {P_{S}\left( t_{2} \right)}}{{P_{S}\left( t_{1} \right)}{P_{S}\left( t_{2} \right)}}}} & (24)\end{matrix}$

As a result, the resistance to collateral flow/ventilation canalternatively be found by solving Eq. 15 for R_(coll) and subsequentsubstitution into Eq. 15 of C_(S) from Eq. 24 and C_(L) from Eq. 25 as

$\begin{matrix}{R_{coll} = \frac{\tau_{coll}}{C_{eff}}} & (25)\end{matrix}$where C_(eff) is the effective compliance as defined in Eq. 15.

Additional Useful Calculation for Check and Balances of all Volumes.

The degree of hyperinflation in the rest of the lobe, hence q_(L)(0),can be determined by solving Eq. 17 for q_(L)(0) and subsequentlysubstituting q_(S)(t₂)+q_(L)(t₂) from Eq. 21 into Eq. 17 afterappropriate solution of Eq. 21 for q_(S)(t₂)+q_(L)(t₂). Thus

$\begin{matrix}{{q_{L}(0)} = {q_{he} \cdot \left( \frac{{F_{{he}_{s}}\left( t_{1} \right)} - {F_{{he}_{s}}\left( t_{2} \right)}}{{F_{{he}_{s}}\left( t_{1} \right)}{F_{{he}_{s}}\left( t_{2} \right)}} \right)}} & (26)\end{matrix}$

Equation 26 provides an additional measurement for check and balances ofall volumes at the end of the clinical procedure.

Regardless of the method of quantifying collateral ventilation, themagnitude of collateral ventilation is dependent on the patient'srespiratory mechanics. For instance, a patient that is breathing veryshallow at −2 cmH₂O of pleural pressure creates a minimal amount of lungcompartment expansion and hence the collateral channels remain somewhatresistive. The measured collateral ventilation will therefore becorrespondingly low. Conversely, if a patient is breathing deep at −10cmH₂O of pleural pressure, a lot of lung expansion takes place whichstretches the effective cross-sectional area of the collateral channelsand hence the collateral channels become less resistive to flowresulting in a commensurate increase in collateral ventilation(references where Rcoll=f(V) as in Woolcock's 1971 or Inners' 1979, andreferences with and Rcoll=f(P) as in Robinson's 1978 and Olsen's 1986).Even in the ideal situation where the resistance to collateral channelsremains independent of effort, greater effort translates into greaterairflow (Baker's 1969 paper).

Therefore, an aspect of the present invention includes measuring thepatient breathing effort so that the collateral ventilation measurementcan be calculated as a function of the degree and/or frequency of thateffort, in effect normalizing the measurement to any situation. Thebreathing effort can be measured in terms of tidal volume inspired bythe patient, or by inspiratory flow rate, peak inspiratory flow rate,pleural pressure created (for example as measured by an esophagealpressure transducer), upper airway pressure, work-of-breathing in joulesof energy exerted per liter of air inspired, thoracic cavity expansion(such as measured by chest wall expansion) or other means. FIGS. 13A-13Cillustrate changes in measured variables based on degree of effort, i.e.during shallow and deep breathing. For example, FIG. 13A illustratespressure measurements in a target lung compartment. At t=0 (t₀), thereis a change in respiratory effort so that the depth of inspiration isincreased. Consequently the amplitude of the pressure wave is increased.Similarly, referring to FIG. 13B, the corresponding volumetric flow ratewave also increases in amplitude at t=0 (t₀) with a larger mean flowrate leaving the target lung compartment as a result. And, referring toFIG. 13C, the volume leaving the target lung compartment and accumulatedover time, such as within a specialized container, may be calculated byintegration of the volumetric flow rate data from FIG. 13B. As shown,the slope of the volume curve changes at t=0 (t₀). The slope denotingthe change in volume over time corresponds to the mean flow rate.

In some embodiments, a specially configured breathing effort sensor isprovided. Such sensors include but are not limited to a mouthpiece thatallows for simultaneous passage through the mouth of the isolationcatheter 10 and measurement of airflow through the mouthpiece (aroundthe outside of the catheter shaft).

FIGS. 14A-14B illustrate changes in measured variables based onfrequency of effort, i.e. during fast and slow breathing. For example,FIG. 14A illustrates volumetric flow rate measurements in a target lungcompartment. At t=0 (t₀), there is a change in respiratory frequency sothat the frequency of respiration is decreased or slowed down resultingin a smaller mean flow rate leaving the target lung compartment.Similarly, referring to FIG. 14B, the volume accumulated over time, suchas within a specialized container, may be calculated by integration ofthe volumetric flow rate data from FIG. 14A. As shown, the slope of thevolume curve changes at t=0 (t₀) indicating smaller volumetric increasesper breath. The slope denoting the change in volume over timecorresponds to the mean flow rate.

The units of measure of the collateral ventilation variable, which takesinto account the degree and/or frequency of the involved respiratoryeffort, are therefore reported in units of A/B where A is themeasurement of collateral ventilation and B is the measurement ofrespiratory drive. The result of the normalized collateral ventilationvariable can be reported, for example, as but not limited to an average,a peak value or a range. Thus, it should be recognized that the desiredmeasurement and reporting of the collateral ventilation normalizedresult includes a mathematical relation and in its most convenient form,a system and the necessary devices to acquire all the needed measuredparameters in a single instrument to apply the said mathematicalrelation to perform the calculation.

It should be appreciated that the normalization technique subject tothis invention is independent of the exact collateral ventilationmeasurement method; any collateral ventilation measurement method can beused with this novel normalization technique.

In some embodiments, detection of collateral ventilation is assistedwith the application of medically safe continuous positive airwaypressure (CPAP), as illustrated in FIG. 15. As shown, the targeted lungcompartment is isolated as previously described with the placement of anisolation catheter into the targeted lung compartment of the patient P.In this embodiment, the isolation catheter is placed with the use of abronchoscope 60 providing an endoscopic view with the use of a monitor62. CPAP is administered via a nasal or oral-nasal non-invasive mask 64,positionable over the patient's face, which is connected to a CPAPventilator 66. This specially configured mask 64 simultaneously allowsfor the administration of CPAP, the passage of the isolation catheter,and optionally breath sensors to measure breathing effort. The isolatedtarget lung compartment is not subjected directly to CPAP, however ifcollateral channels are present, the detection of these channels isfacilitated because the CPAP amplifies the degree of airflow across thechannels due to simple pressure gradient laws. Further hyperinflationdue to air trapping is prevented using safe pressure levels and I:Eratios. Therefore, CPAP increases the measurement sensitivity of thecollateral ventilation measurement technique of using an externallyplaced but communicating flow meter or special container.

FIG. 16A illustrates example collateral flow measurements recorded by aflow meter. At t=0 (t₀), the CPAP mask is positioned on the patient andshortly thereafter CPAP is started resulting in an amplified signal.Thus, prior to t=0 (t₀) the flow signal 70 is relatively weak showingspontaneous breathing without CPAP. After t=0 (t₀), the flow signal 70′is stronger showing an amplification of the flow rate signal due toCPAP. Similarly, FIG. 16B illustrates example pressure measurementstaken in lung compartments that are not isolated by the isolationcatheter (the pressure in the isolated lung compartment is less, closerto normal). At t=0 (t₀), the CPAP mask is positioned on the patient andshortly thereafter CPAP is started resulting in an amplified signal.Thus, prior to t=0 (t₀) the pressure signal 72 is relatively weakshowing spontaneous breathing without CPAP. After t=0 (t₀), the pressuresignal 72′ is stronger showing an amplification of the pressure signaldue to CPAP.

In some embodiments, a single breath technique is used wherein thecollateral ventilation and, if so measured, the patient's breathingeffort, are measured for a single breath. Referring to FIG. 17, thetargeted lung compartment C_(s) is cannulated and isolated with anexternally communicating catheter 10 as previously described. Here, thepatient P is shown having the catheter 10 advanced into the targetedlung compartment C_(s) and the flowmeter 18 and/or pressure sensor 20and one-way valve 16 residing outside of his mouth. The flowmeter 18and/or pressure sensor 20 is linked to a computer 80 which acquires theappropriate data. Example flow rate 82 and pressure curves 84 are shown.The cooperative patient P is instructed to breath out as much air aspossible with a forced and extended exhalation effort (t₁), and at theend of exhalation (which is detectable with the breath sensing devices)the target lung compartment C_(s) is isolated (t₂). The patient theninitiates a maximal inspiratory effort (t₃) and starts a deep exhalation(t₄) which then ends at (t₅). It is presumed that any air exiting theisolation catheter 10 during the deep exhalation (t₄-t₅) would be fromcollateral ventilation. If collaterals were present, a flow peak 86 anda pressure peak 88.

The collateral ventilation (and breathing effort if so measured) can bemeasured and reported as a function of a single breath peak inspiratoryeffort. Results can be reported normalized or unnormalized for thecomplete breath, a peak value during the breath, an average value duringthe breath, the value during a portion of the breath, for example butnot limited to the first one second of the breath, an average value of anumber of separate single breath measurements or maneuvers. Theprocessing unit in the case of this embodiment includes the requisitealgorithms and control systems to obtain and process the measurement asneeded.

In additional embodiments, airflow measurements are made both before,during and after isolation of the targeted lung compartment C_(s),wherein such measurements are analyzed to evaluate collateralventilation. For example, an external flow measuring device isconfigured to measure flow into and out of a targeted lung compartmentC_(s) via an externally communicating catheter 10 placed into thecompartment C_(s), as previously described. First, the compartment C_(s)is cannulated with the catheter 10, but without isolating the bronchus.Referring to FIG. 18A, the flow measurement through the catheter lumenis made, resulting in a flowrate curve 90 at baseline. Second, while theflow measurement continues, the bronchus is isolated by inflating theoccluder balloon and the amplitude of the flowrate curve 90 increases ifthere is collateral flow. Then, while the flow measurement continues,the occluder balloon is deflated and the flowrate curve 90 decreasesback to baseline. Corresponding volume and pressure measurement curvesare shown in FIG. 18B and FIG. 18C respectively. Comparison of theairflow magnitude and direction as measured at the external flow-sensingdevice provides additional information about the collateral channels inthe target compartment and/or verification of the system's integrity.For example, comparison of the amplitudes before and after isolation canalso be used to quantify/or normalize the degree of flow via collateralchannels and/or check for adequate isolation of the target compartment.This aspect of the invention includes the requisite systems and devicesfor processing the pre and post airflow measurements and may include anautomatic isolation system controlled by instrumentation embedded in theprocessing unit.

In an additional embodiment of the present invention, as illustrated inFIG. 19, flow is measured via a catheter 10 as previously described. Theocclusion member 14 is positioned and inflated to isolate the targetlung compartment C_(s). As the patient breathes, both the target lungcompartment C_(s) and the non-target compartment C expand and recoil asshown. The measured flow data 92 is closely inspected to compare thewaveforms obtained during inspiration and exhalation (inhalationwaveform=VI, exhalation waveform=VE). The ratio VI/VE in the presence ofcollateral ventilation differs from the ratio VI/VE in the absence ofcollateral ventilation. These and other differences in the waveformcharacteristics of inspiration versus exhalation shall facilitatedetermining whether collateral ventilation exists.

In some embodiments, as illustrated in FIGS. 20A-20B, the isolationcatheter 10 includes a fiberoptic endoscope, or bronchoscope 100, withoptional built-in imaging, illumination and/or steering. FIG. 20Aillustrates the bronchoscope 100 inserted into an external sheath 102having an occlusion member 104 and joined at a sheath proximal connector106. Exemplary embodiments of suitable external sheaths having inflationcuffs for use with bronchoscopes or other endoscopic instruments aredescribed in U.S. Pat. No. 6,585,639, incorporated herein by referencefor all purposes. FIG. 20B provides a more detailed illustration of thedistal end of the bronchoscope 100 and sheath 102 of FIG. 20A. Thus, aworking channel 103 of the bronchoscope 100 is shown along with imagingfeatures 105. Referring back to FIG. 20A, the bronchoscope 100 andsheath 102 are advanced down the trachea T of the patient P to thetarget lung compartment C_(s) so that the inflation cuff 104 ispositioned to isolate the target lung compartment C_(s). The sheath 102also includes a cuff inflation line/valve 108 which can be used tomeasure cuff pressure. The bronchoscope 100 includes an imaging cable110 and light cable 112, as shown. Optionally, a suction line 114 mayalso be connected with the bronchoscope 100. The shaft of thebronchoscope includes a lumen extending most of its length to which aflow-measuring device 116 is connected external to the patient P. Asshown, the flow-measuring device 116 has a power cord 118 and a signalto main processor 120. Tubing 122 connects the bronchoscope 100 to aninlet 124 of the flow-measuring device 110, wherein a check valve 126 ispresent along the tubing 122. Air, gasses or other measured entities arereleased from the flow-measuring device 116 via an outlet 128. Thesheath 102 or an outer sleeve may be equipped with additional lumensthat extend across the occlusion member 104 for the purpose of measuringflow or other respiratory or physiological parameters, or for deliveringagents or tracer gases.

Alternatively, in the absence of a sheath 102 having an occlusion member104, a special catheter may be inserted into the lumen of thebronchoscope 100 and can be used to access the targeted lung compartmentC_(s). The catheter may to create the isolation seal by any appropriatemeans, including creating an isolation seal with an inflatable elementmounted on the distal end of the catheter or by connecting with orpassing through an occlusal stent which is positioned to seal thebronchial lumen. For example, FIGS. 21A-21C illustrate the performanceof a collateral ventilation test through an occlusal stent 130.Referring to FIG. 21A, an occlusal stent 130 is shown sealing abronchial lumen leading to a target lumen compartment C_(s). Abronchoscope 100 is shown advanced to a position near the occlusal stent130. Referring to FIG. 21B, a catheter 132 is advanced through thebronchoscope 100 and through the occlusal stent 130, accessing thetarget lung compartment C_(s). The occlusal stent 130 includes a valvewhich allows the catheter 132 to advance therethrough while maintainingisolation of the target lung compartment C_(s). Measurements ofpressure, flow or other respiratory or physiological parameters are thentaken, with or without a one-way valve and/or external specialcontainer, either at the tip of the catheter 132 in the targeted lungcompartment C_(s) or at the proximal end of the catheter 132, externalto the patient, through a lumen in the catheter 132 that extends thecatheter's length. When accessing through an occlusal stent 130, volumereduction therapy may then be performed by aspirating through thecatheter 132 and stent 132, as illustrated in FIG. 21C. The catheter 132is then removed and the volume reduction maintained.

In a similar but further embodiment, gas temperature is measured at somepoint along the catheter lumen either instead of the flow ratemeasurement or to complement the flow rate measurement, in order tofurther interpret the data being collected and/or to further distinguishbetween expiratory flow and inspiratory flow through the catheter lumen.

In a still further embodiment of the present invention, respiratory gascomposition of the target lung compartment C_(s) is measured tofacilitate further interpretation of the airflow data gathered by a flowmeasuring device. Such measurement may be taken separately orsimultaneously with the flow rate measurements. For example, a certaindecay rate of O₂ composition in the gas at the external end of thecatheter may be indicative of no or little collateral flow, whereas aslower or no decay rate of O₂ may be indicative of collateral flow sincefresh oxygen inspired by the patient can enter the target compartmentC_(s) via the collateral channels. Other gases, for example CO₂, canalso be measured, as illustrated in FIGS. 22A-22C. FIG. 22A illustratesa catheter 140 advanced through a bronchoscope 100 having an occlusionmember 142 which seals a bronchial lumen leading to a target lumencompartment C_(s). The catheter 140 is connected with a flow sensingdevice 144, as described above. In addition, the catheter 140 isconnected with a gas sensing device 146, such as a capnographer, havinga gas sensor 148. Measurements of flow or other respiratory orphysiological parameters are then taken, with or without a one-way valve149 and/or external special container, either at the tip of the catheter140 in the targeted lung compartment C_(s) or at the proximal end of thecatheter 140, external to the patient, through a lumen in the catheter140 that extends the catheter's length. FIG. 22B-22C illustrate exampleflow measurements 150 recorded by the flow sensing device 144, alongwith corresponding CO₂ concentration measurements 152. FIG. 22Billustrates a situation wherein there is no collateral flow between thetarget compartment C_(s) and a neighboring compartment C. FIG. 22Cillustrates a situation wherein there is collateral flow between thetarget compartment C_(s) and the neighboring compartment C. Asillustrated, differences can be seen in both the flow measurements 150and CO₂ concentration measurements 152. Therefore, measurement ofvarious gases can be used to complement flow measurements for datainterpretation. The gas composition together with the flow data can alsobe used to normalize the collateral flow measurement as previouslydescribed.

In yet another embodiment of the present invention, tracer gas infusionand measurement may be used to facilitate further interpretation of theairflow data gathered by a flow measuring device. Measurement of thecomposition of tracer gas, simultaneous with the measurement of airflowas previously described, will facilitate distinguishing between air froma neighboring lung compartment C entering through collateral channelsand air that was native to the targeted isolated lung compartment C_(s).Typically the tracer gas is inert and is not absorbed by the tissue orblood stream in order to eliminate that variable in the collateral flowmeasurement, however optionally the gas can be a diffusible orabsorbable gas for purposes described later. FIG. 23A illustrates acatheter 154 advanced through a bronchoscope 100 having an occlusionmember 156 which seals a bronchial lumen leading to a target lumencompartment C_(s). The catheter 154 is connected with a flow sensingdevice 158, as described above. In addition, the catheter 154 isconnected with a tracer gas sensing device 160 and a tracer gasinjection device 162, such as a syringe. Measurements of flow or otherrespiratory or physiological parameters are then taken, with or withouta one-way valve and/or external special container, either at the tip ofthe catheter 154 in the targeted lung compartment C_(s) or at theproximal end of the catheter 154, external to the patient, through alumen in the catheter 154 that extends the catheter's length. FIG.23B-23C illustrate example flow measurements 164 recorded by the flowsensing device 166, along with corresponding tracer gas concentrationmeasurements 168. FIG. 23B illustrates a situation wherein there is nocollateral flow between the target compartment C_(s) and a neighboringcompartment C. As shown, tracer gas concentration remains steady. FIG.22C illustrates a situation wherein there is collateral flow between thetarget compartment C_(s) and the neighboring compartment C. Asillustrated, the tracer gas concentration decays due to leakage throughcollateral channels. The tracer gas decay rate and flow measurements maybe compared arithmetically to determine if collateral channels arepresent and/or the magnitude or size of the channels.

In still another embodiment of the present invention, absorbable gasinfusion and measurement may be used to facilitate furtherinterpretation of the airflow data gathered by a flow measuring device.Measurement of the composition of absorbable gas (such as oxygen),simultaneous with the measurement of airflow as previously described,will facilitate distinguishing between air from a neighboring lungcompartment C entering through collateral channels and air that wasnative to the targeted isolated lung compartment C_(s). FIG. 24Aillustrates a catheter 170 advanced through a bronchoscope 100 having anocclusion member 172 which seals a bronchial lumen leading to a targetlumen compartment C_(s). The catheter 170 is connected with a flowsensing device 174, as described above. In addition, the catheter 170 isconnected with a gas delivery system 176 and gas source 178. The gasdelivery system 176 and flow sensing device 174 are connected with thecatheter 170 via a switching valve 180 which allows the flow sensingdevice 174 to monitor collateral flow after the absorbable gas isdelivered. Measurements of flow or other respiratory or physiologicalparameters are then taken, with or without a one-way valve and/orexternal special container, either at the tip of the catheter 170 in thetargeted lung compartment C_(s) or at the proximal end of the catheter170, external to the patient, through a lumen in the catheter 170 thatextends the catheter's length. FIG. 23B-23C illustrate example flowmeasurements 182 recorded by the flow sensing device 174, along withcorresponding absorbable concentration measurements 184. FIG. 23Billustrates a situation wherein there is no collateral flow between thetarget compartment C_(s) and a neighboring compartment C. As shown,absorbable gas concentration decays via blood diffusion. FIG. 22Cillustrates a situation wherein there is collateral flow between thetarget compartment C_(s) and the neighboring compartment C. Asillustrated, the absorbable gas concentration decays at a faster ratedue to diffusion and leakage through collateral channels. The absorbablegas decay rate and flow measurements may be compared arithmetically todetermine if collateral channels are present.

To assist in accuracy of collateral flow measurements and othermeasurements, devices and methods are provided for seal testing of theisolation catheter. FIG. 25A illustrates a distal end of an isolationcatheter 10 having an occlusion member 14 mounted thereon. The occlusionmember 14 is shown inflated within a lung passageway LP. It is desiredthat the occlusion member 14 seals effectively to occlude the passagewayLP, otherwise leakage by the occlusion member 14 may, for example, bemistaken for collateral flow thereby introducing error to the collateralflow measurements. Therefore, leak-testing may be performed to ensureappropriate seal. In one embodiment, the isolation catheter 10 includesa gas delivery lumen 200 and a gas sampling lumen 202. The gas deliverylumen 200 exits the catheter 10 distally of the occlusion member 14,such as through a delivery port 204, as illustrated. The gas samplinglumen 202 exits the catheter 10 proximally of the occlusion member 14,such as through sampling port 206. FIG. 25B illustrates across-sectional view of FIG. 25A and shows the gas delivery lumen 200and gas sampling lumen 202 extending through the wall of the catheter 10while a main lumen 208 extends throughout the length of the catheter 10.An inert gas is introduced through the isolation catheter 10 and isdelivered through the delivery port 204. As illustrated in FIG. 25C,concentration of the inert gas within the lung passageway LP (or withina target compartment to which the lung passageway is connected) remainssteady immediately after introduction of the gas, as indicated by curve210. A vacuum is applied to the sampling lumen 202, as indicated bycurve 212. In the case of an insufficient seal, gas leakage between theocclusion member 14 and the wall of the lung passageway LP will besuctioned into the sampling lumen 202 and measured, as indicated bycurve 214. Such a leak test may be manual, automatic, or sem-automatic.Any processing/control unit external to the body for collateralventilation testing may include the requisite controls and measuringdevices for such leakage measurements.

It may be appreciated that in other embodiments, seal testing mayalternatively or in addition be achieved by monitoring pressure withinthe occlusion member 14. Referring back to FIG. 25B, an inflation lumen216 is shown extending through the wall of the isolation catheter 10.Typically, the inflation lumen 216 extends to the occlusion member 14 topass fluid to the occlusion member 14 for inflation. However, in thisembodiment the inflation lumen 216 is attached at its proximal end to apressure gauge to measure pressure within the occlusion member 14. Ifthe measured pressure falls below a desired level for adequate sealing,the pressure may be increased automatically or manually. Such pressuremeasurements may be taken continuously or semi-continuously.

FIG. 26 illustrates an embodiment of a system of the present inventionfor measuring collateral ventilation in one or more lung passageways ofa patient. Here, the system includes a bronchoscope 100 inserted into anexternal sheath 102 having an occlusion member 104 and joined at asheath proximal connector 106. A working channel 103 extends within thebronchoscope 100 to a side port 231 (for introduction of a catheter orother instrument to the working lumen 103) and a connector 230. Asuction line 232 connects the working channel 103 with wall suction viathe connector 230. In addition, the connector 230 is used to connect theworking channel 103 with a control valve 236. The control valve 236 isin turn connected with an electronic unit 238 which includes anelectronic control module, a signal acquisition unit and a signalprocessing unit. In this embodiment, the electronic unit 238 also housesan oxygen delivery compartment 240 containing oxygen for deliverythrough an oxygen line 242 to the control valve 236 and to the workinglumen 103 of the bronchoscope 100. In addition, a carbon dioxide sensor246 is provided which is connected to a carbon dioxide line 248 whichalso connects with the control valve 236 and the working lumen 103.Further, a flow meter 250 is connected to a collateral ventilation line252 which also connects with the control valve 236 and the working lumen103. The control valve 236 is manipulated by control signals 254 sentfrom the electronic unit 238. A display 256 is also connected with theelectronic unit 238 for visual display of measurement data. In thisembodiment, the system also includes a pressure transducer 258 which isconnected with the occlusion member 104 via an inflation line 260. Theinflation line 250 also includes an inflation port 262 for introducingan inflation fluid to the occlusion member 104. The system of FIG. 26may be used to perform a variety of the methods, measurements andtreatments described herein.

It may be appreciated that any and all possible combinations of theembodiments described herein can be employed. For example, an externalspecial container filled with O₂ connected to a targeted compartment viaan isolation catheter is included at least by means of using theconstituent parts of separate embodiments. Or, for example two of theabove embodiments can be combined such that two external specialcontainers are filled with different tracer gases and the specialcontainers connected each to separate isolation catheters that are eachisolating neighboring lung areas; analysis of the flow and gascomposition in the special containers after a number of breaths may becorrelative to collateral ventilation between the areas.

Systems, methods and devices of the present invention may be used toevaluate any number of target compartments C_(s) within the lungs of apatient. In particular, levels of collateral ventilation may be mappedto the target compartments so that the practitioner may determine theoverall condition of the patient and the most desired course oftreatment. For example, the right upper lung lobe (RUL) may be isolatedand tested for collateral ventilation between it and the neighboringright middle lobe (RML). After the measurement is taken, the isolationcatheter may be advanced deeper into the tracheobronchial tree to, forexample, the apical segment of the right upper lobe and that segment canbe tested for collateral ventilation between it and the neighboringanterior segment and posterior segments. As such, the diagnostictechniques described herein can be used to diagnostically map an area ofthe lung, or the complete lung with respect to collateral ventilation.FIG. 27 illustrates an embodiment of a screen 280 indicating suchmeasurements and mapping, wherein such a screen 280 may be seen on thedisplay 256 of FIG. 26. Here, the screen 280 shows bar graphs 282indicating a numerical value of collateral ventilation (or collateralventilation resistance) between specific lung areas. For example, a bargraph 282 is shown between the RUL and RML indicating the numericalvalue of collateral ventilation between these two lobes. In addition,bar graphs 282 are shown between individual segments within each lobe.For example, the RUL has target compartments denoted B1, B2, B3, the RMLhas target compartments denoted B4, B5, B6, and B7, and the right lowerlobe (RLL) has target compartments denoted B8, B9, and B10. Likewise,the left upper lobe (LUL) has target compartments denoted B1, B2, B3,B4, B5, and B6, and the left lower lung (LLL) has target compartmentsdenoted B8, B9, B10. A bar graph 282 extending between B1 and B2 withinthe RUL indicates a numerical value of collateral ventilation (orcollateral ventilation resistance) between the specific B1 and B2 targetcompartments. In addition, the screen 280 includes a visual depiction284 of at least a portion of the lungs mapping the collateralventilation data to the appropriate areas of the lungs. For example, thevisual depiction 284 may include fissures between the lobes or targetcompartments wherein the shading of the fissure indicates thecompleteness of the fissure. In some embodiments, a darker fissureindicates a complete fissure and a lighter fissure indicates anincomplete fissure. Alternatively or in addition, a user may select anarea of interest to display a cut-away view of the fissures in theselected area of interest. In addition, the screen 280 may include alink button 286 which changes the screen 280 to another screen 280′depicting measurement data of other variables, such as gas exchange dataor other diagnostic measurement data. Thus, the practitioner may usesome or all of the visual information provided to assess the conditionof the patient and determine the treatment plan.

FIG. 28 illustrates an embodiment of a method 300 of treating a patient.In this embodiment, the patient is referred by a non-specialist to aspecialist in lung disease and treatment 302. The patient then undergoescomputed tomography (CT) 304 to produce detailed images of structuresinside the body, particularly the lungs. A CT scanner directs a seriesof X-ray pulses through the body. Each X-ray pulse lasts only a fractionof a second and represents a “slice” of the organ or area being studied.The slices or pictures are recorded on a computer and can be saved forfurther study or printed out as photographs. The patient also undergoespulmonary function testing (PFT) 304. PFT is a breathing test or seriesof tests to determine, for example, maximum volume of air the lungs canhold, how fast the patient can move air into and out of their lungs, andhow easy it is for gas to pass from the lungs to the blood and thesurface area available for gas movement. Bronchoscopy with collateralventilation testing 306 is then performed on the patient. If nocollateral ventilation (or a level of collateral ventilation below athreshold) is measured, Endobronchial Volume Reduction (EVR) 308 may beperformed on the patient. If collateral ventilation (or a level ofcollateral ventilation above a threshold) is measured, some or all ofthe collateral flow channels may be treated 310 (e.g. obliterated orclosed), such as with the use of RF, NaCl, sticky substances,perflubron, HF ultrasound, sclerosing agents, heating agents or thelike.

Bronchoscopy with collateral ventilation testing 306 may then beperformed again on the patient. If no collateral ventilation (or a levelof collateral ventilation below a threshold) is measured, EndobronchialVolume Reduction (EVR) 308 may be performed on the patient. Ifcollateral ventilation (or a level of collateral ventilation above athreshold) is still measured, some or all of the collateral flowchannels may be additionally be treated 310. FIG. 29 illustrates anexample iterative process of reducing collateral ventilation prior toEVR. An example limit 290 of collateral flow that is desired forsuccessful EVR (i.e. the measurement of collateral flow should be belowthis level in order to perform EVR) is illustrated. Flow curve 292 priorto t₁ shows collateral flow that is above the limit 290. The collateralflow channels are then treated. As shown, the flow curve 292 between t₁and t₂ is reduced but still above the limit 290. The collateral flowchannels are then further treated. As shown, the flow curve 292 betweent₂ and t₃ is further reduced but still above the limit 290. Thecollateral flow channels are then further treated. As shown, the flowcurve 292 beyond t₃ is now below the limit 290 and the patient may betreated with EVR.

Referring back to FIG. 28, in addition to bronchoscopy with collateralventilation testing 306, lung mapping 312 may be performed. If the lungmapping indicates no collateral ventilation (or a level of collateralventilation below a threshold), Endobronchial Volume Reduction (EVR) 308may be performed on the patient. If the lung mapping indicatescollateral ventilation (or a level of collateral ventilation above athreshold) is measured, some or all of the collateral flow channels maybe treated 310. Such mapping may be repeating after repeatedbronchoscopy with collateral ventilation testing 306.

Devices, systems and methods of the present invention may also be usefulto assess the sealing or valving performance of any endobronchialprosthesis, such as occlusal stents, plugs, one-way valves or otherdevices used in endobronchial lung volume reduction procedures. Examplesof such devices are described in U.S. Pat. No. 6,287,290, “METHODS,SYSTEMS AND KITS FOR LUNG VOLUME REDUCTION”, and U.S. Pat. No.6,527,761, “METHODS AND DEVICES FOR OBSTRUCTING AND ASPIRATING LUNGTISSUE SEGMENTS”, each incorporated herein by reference for allpurposes. Devices, systems and methods of the present invention may alsobe useful to assess the lung for leaks communicating with the pleuralspace (such as leaks arising from lung volume reduction surgery, otherlung surgeries, or spontaneous pneumothorax). In either case, this maybe achieved by introducing a catheter to and isolating the lungcompartment of interest as previously described and performing the flowmeasurement as previously described, with or without a check valve. Forexample in the case of a bronchial occlusal stent, the flow measurementwill indicate no inspiratory or expiratory flow if the stent iseffectively sealing, but will show flow if the stent is not sealing.One-way valves can be assessed similarly. If the valve is intended toallow expiratory flow but prevent inspiratory flow, the flow measuringdevice should detect flow during exhalation but not detect flow in theexpiratory direction. Should flow be detected during inspiration, thevalve may be inadvertently leaking Should no flow be detected in theexhalation direction (assuming the valved area is not atelectatic), thevalve may be inadvertently plugged.

With reference now to FIGS. 30A-30D, a system 410 for determiningwhether collateral ventilation into a portion of a lung exists is shown.In this embodiment, system 410 includes a catheter 412 having anocclusion member 414 coupled with its distal region, a one-way valve 420coupled with its proximal region, a hub 416 and a syringe 418 coupledwith hub 416 and in fluid communication with an inflation lumen ofcatheter 412 to inflate occlusion member 414. System 410 also includes ahousing 422, in which one-way valve 420 and a video camera 422 arehoused, and a video monitor 428 coupled with camera 422 via a cable 426.In the embodiment shown, occlusion member 414 is an inflatable balloon,though in other embodiments a different occlusion device may be used.

FIG. 30B shows a close-up side cutaway view of housing 422 with one-wayvalve 420 and camera 424 positioned therein. In various embodiments,valve 420 may be housed within housing 422 and housing may be coupledwith a proximal end of catheter 412, or valve 420 may be housed withinthe proximal end of catheter 412 and catheter 412 (with valve 420inside) may extend into housing 422. In yet other embodiments, housing422 may be eliminated altogether. In any case, one-way valve may bevisualized via the naked eye or via camera 424 and video monitor 428. Inembodiment including housing 422, video camera 424 is positioned withinhousing 422 in such a way to face valve 420 to view opening and closingthereof. The images captured by camera 424 are then displayed on videomonitor 428 as video images 430. In some embodiments, these images 430may be superimposed over or positioned next to one or more other imagesor readouts, such as graphs, charts or other data that have been or arebeing simultaneously collected about the patient.

In use, catheter 412 may be advanced into a patient's airways toposition occlusion member 414 in an airway AW leading to a target lungcompartment (a portion of an airway AW is shown in FIG. 30Aschematically). In various embodiments, the airway may be a bronchusleading to a lobe of a lung or a smaller airway (bronchiole) leading toa segment of a lung. Thus “airway” refers broadly to any airway feedinga target lung compartment (lobe or segment) other than a collateralpathway. After the catheter 412 and occlusion member 414 are positionedas desired and occlusion member 414 is expanded to occlude the airwayAW, the patient is allowed to breathe freely. On inhalation, air will beprevented from passing through the airway AW into the target lungcompartment by occlusion member 414. On exhalation, air will pass fromthe target lung compartment through a lumen in catheter 412 andsubsequently through one-way valve 420, thus causing valve 420 to openand close. Video camera 424 and video monitor 428 capture video images430 of valve 430 opening and closing. The user, typically a physician,may watch the opening and closing of valve 420 over time to determinewhether there is significant collateral ventilation into the target lungcompartment. If there is significant collateral ventilation, valve 420is expected to continue to open and close over time. If there is nosignificant collateral ventilation, valve 420 should stop opening andclosing, because the target lung compartment should empty out over time.Based on the observation of the opening and closing of valve 420, thephysician can make a determination as to the presence or absence ofcollateral ventilation and may use this determination to decide whether,how and/or where to treat the patient.

Although the foregoing invention has been described in some detail byway of illustration and example, for purposes of clarity ofunderstanding, it will be obvious that various alternatives,modifications and equivalents may be used and the above descriptionshould not be taken as limiting in scope of the invention which isdefined by the appended claims.

What is claimed is:
 1. A system for detecting collateral ventilationinto a lung compartment in a patient, the system comprising: a catheterhaving a lumen and adapted to be introduced transtracheally to abronchus leading to a target lung compartment; an occlusion member on adistal region of the catheter, said occlusion member being adapted toselectively occlude the bronchus; a one-way valve coupled with aproximal region of the catheter and in fluid communication with thelumen; a video camera adapted to capture video images of the one-wayvalve; and wherein the occlusion member is configured to be deployed inthe bronchus to prevent air from being inhaled into the target lungcompartment through the bronchus, wherein the catheter is configured toallow air exhaled from the target lung compartment to pass through thelumen and the one-way valve, and wherein the catheter has sufficientoverall length so that the one-way valve is located outside the patientduring use.
 2. A system as in claim 1, wherein the video cameracomprises a USB camera.
 3. A system as in claim 1, wherein the videocamera is coupled with the proximal region of the catheter.
 4. A systemas in claim 3, wherein the video camera is coupled with a housingmember, wherein the one-way valve is coupled with the housing member,and wherein the proximal region of the catheter is coupled with thehousing member.
 5. A system as in claim 1, further comprising a videomonitor for displaying the video images captured by the video camera. 6.A system as in claim 1, wherein the one-way valve is removably coupledwith the catheter.
 7. A system as in claim 6, wherein the one-way valvecomprises an endobronchial valve device.
 8. A system as in claim 1,wherein the one-way valve is housed inside a housing member that isremovably coupled with the proximal region of the catheter.
 9. A systemfor detecting collateral ventilation into a lung compartment in apatient, the system comprising: a catheter having a lumen and adapted tobe introduced transtracheally to a bronchus leading to a target lungcompartment; an occlusion member on a distal region of the catheter,said occlusion member being adapted to selectively occlude the bronchus;a one-way valve coupled with a proximal region of the catheter and influid communication with the lumen; a filter coupled with the catheterto filter exhaled air traveling through the catheter to the valvewherein at least a portion of the catheter distal to the filter isremovable from the system; and wherein the occlusion member isconfigured to be deployed in the bronchus to prevent air from beinginhaled into the target lung compartment through the bronchus, whereinthe catheter is configured to allow air exhaled from the target lungcompartment to pass through the lumen and the one-way valve, and whereinthe catheter has sufficient overall length so that the one-way valve islocated outside the patient during use.